Check Strap Fatigue

I've got a 2000 323Ci and have been hearing a click from the drivers door when I open it. The click became a bang leading me to find the source. Metal
fatigue!! The metal has cracked where the checkstrap bolts on. I've just had the car back from the dealer cos it had the dreaded subframe tear out. They repaired that through the warranty even tho the car was registered in 2000. Does anyone know if this fault is common and can I claim on the bodywork warranty. The checkstrap will breakout soon if I don't do something. BTW i've got an inspection 2 due very soon. Any help appreciated.
Cheers Rich

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